I recently used this fin on a 4 day trip in Missouri down Jack's Fork river on my ISUP. In some areas the water was only a few inches deep, however, I was able to float by. The person I was with was using a kayak and had to get out and walk it many times. The flexibility of the fin is appropriate at keeping the board straight while being flexible enough when rocks get in the way. I'm giving 4 stars because, the screw at the front which holds the fin eventually sheared when I bumped into a rock. Ultimately, this caused me to lose the fin. I would suggest using a lower profile thumb screw or keep a spare. I will be buying another because of how this fin performs, however, I'll be looking to get a backup retainer screw or use something stronger.

The fin itself is great for whitewater but I wish they'd move the pin to the back of the fin to prevent rock hits.

Fin get’s a little dinged on rocks but it holds its line and has a nice little flex to it when needed.

Like others here, I wish it was a bit more flexible. Also, it did not quite fit the fin box on my Starboard inflatable, I'm going to need to drill a new hole. Still, seems to be the best option for a low profile center fin for river use.

People that say this fin is completely rigid have no idea what they’re talking about. This fin has considerable flex and is perfect for those skinny water paddles on flats and rivers.